The present invention relates to novel pipes made of polymeric material.
In particular the present invention relates to novel pipes made of polymeric material capable of being used for throttle bodies.
Pipes of this type accommodate within them a mobile gate member, which, by co-operating with the inner wall of the pipe, selectively controls the flow rate of fluid through the pipe itself. It is obvious that in pipes of this type there is a necessity for the inner wall to be constituted by a material that is capable of ensuring effective and extended activity of the throttle valve. Such materials will here and hereinafter be denoted xe2x80x9chigh-performancexe2x80x9d materials.
As is known to the person skilled in the art, high-performance polymeric materials are those polymeric materials that have intrinsic properties such as to give them excellent mechanical, chemical and thermal properties.
In the present invention, the essential property that identifies a high-performance polymeric material is a distortion temperature under load in accordance with standard HDT-A ISO75 of no less than 275xc2x0 C.
High-performance polymeric materials that meet the above-stated requirements have now been available for some time. However, such materials are particularly expensive, to the extent that using them to produce the entire pipe is not really feasible.
One possible solution is to make a pipe having a metal core coated with a high-performance polymeric material. In this solution, the connection between the polymeric material and the metal core is purely mechanical. While such a solution solves the problem relating to the cost of the pipe and to the presence of the high-performance polymeric material in the inner wall, it does suffer from a problem of progressive detachment that, as time passes, occurs between the polymeric part and the metal part of said pipe.
The aim of the present invention is to provide novel pipes having technical properties that free them from the problems of the prior art.
The subject-matter of the present invention is a pipe comprising an inner wall constituted by a first high-performance thermoplastic polymeric material having a distortion temperature under load in accordance with standard HDT-A ISO75 of at least 275xc2x0 C.; said pipe being characterised in that it comprises an outer wall constituted by a second thermoplastic material belonging to the same family of chemical polymers as said first high-performance thermoplastic material.
The pipe is preferably produced by means of coinjection of the first thermoplastic material with the second thermoplastic material.
The first and second thermoplastic materials preferably belong to the family of polyamides or polyesters.
The first and second thermoplastic materials preferably belong to the family of polyamides.